Multi-speed transmission with external drive gearsets

ABSTRACT

A transmission is provided having an input member, an output member, three planetary gear sets, four external gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. Each of the external gear sets includes first and second gears. The torque transmitting devices may include clutches and brakes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/975,419, filed on Sep. 26, 2007. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of gear sets and a plurality of torque transmitting devices,and more particularly to a transmission having eight or more speedsproduced by a combination of planetary gear sets, external gear sets andtorque transmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches or brakes, planetary gear arrangements and fixedinterconnections to achieve a plurality of gear ratios. The number andphysical arrangement of the planetary gear sets, generally, are dictatedby packaging, cost and desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,three planetary gear sets, four external gear sets, a plurality ofcoupling members and a plurality of torque transmitting devices. Each ofthe planetary gear sets includes first, second and third members. Eachof the external gear sets include first and second gear members. Thetorque transmitting devices are for example clutches and brakes.

An embodiment of the transmission includes an input member, an outputmember, a first, second, and third planetary gear set each having afirst, second, and third member, a first, second, third, and fourth gearset each having a first gear intermeshed with a second gear, a firstinterconnecting member continuously interconnecting the first gear ofthe first gear set with the first member of the first planetary gearset, a second interconnecting member continuously interconnecting thethird member of the first planetary gear set with the first gear of thesecond gear set, a third interconnecting member continuouslyinterconnecting the first gear of the third gear set with the secondmember of the second planetary gear set, a fourth interconnecting membercontinuously interconnecting the first member of the second planetarygear set with the second gear of the second gear set, a fifthinterconnecting member continuously interconnecting the first member ofthe third planetary gear set with the first gear of the third gear set,and a sixth interconnecting member continuously interconnecting thesecond member of the third planetary gear set with the first gear of thefourth gear set. Five torque transmitting mechanisms are selectivelyengageable to interconnect one of the first members, second members,third members, first gears, and second gears with at least one of thefirst members, second members, third members, first gears, second gears,and a stationary element. The torque transmitting mechanisms areselectively engageable in combinations of at least three to establish atleast eight forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.

In one aspect of the present invention, a first of the five torquetransmitting mechanisms is selectively engageable to interconnect thesecond gear of the third gear set with at least one of the second memberof the first planetary gear set and the input member.

In another aspect of the present invention, a second of the five torquetransmitting mechanisms is selectively engageable to interconnect atleast one of the third member of the first planetary gear set and thefirst gear of the second gear set with the second gear of the third gearset.

In yet another aspect of the present invention, a third of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe second gear of the first gear set with the third member of the thirdplanetary gear set.

In yet another aspect of the present invention, a fourth of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe third member of the third planetary gear set with the third memberof the second planetary gear set.

In yet another aspect of the present invention, a fifth of the fivetorque transmitting mechanisms is selectively engageable to interconnectat least one of the first gear of the first gear set and the firstmember of the first planetary gear set with the stationary element.

In yet another aspect of the present invention, the first and secondtorque transmitting mechanisms are connected to the second gear of thethird co-planar gear set by a first sleeve shaft, the fifth torquetransmitting mechanism is connected to the first gear of the firstco-planar gear set and the first member of the first planetary gear setby a second sleeve shaft, and the first and second sleeve shafts areconcentric with the input member.

In yet another aspect of the present invention, the first and secondtorque transmitting mechanisms are connected to the second gear of thethird co-planar gear set by a first sleeve shaft, the fifth torquetransmitting mechanism is connected to the first gear of the firstco-planar gear set and the first member of the first planetary gear setby a second sleeve shaft, and the first and second sleeve shafts areconcentric with the input member.

In yet another aspect of the present invention, the input member iscontinuously interconnected with the second member of the firstplanetary gear set and the output member is continuously interconnectedwith the second gear of the fourth gear set.

In yet another aspect of the present invention, the first members aresun gears, the second members are carrier members, and the third membersare ring gears.

In yet another aspect of the present invention, the first members of thefirst and third planetary gear sets are sun gears, the second members ofthe first and third planetary gear sets are carrier members, the thirdmembers of the first and third planetary gear sets are ring gears, thefirst member of the second planetary gear set is a carrier member, thesecond member of the second planetary gear set is a sun gear, and thethird member of the second planetary gear set is a ring gear.

In yet another aspect of the present invention, the first gears and thesecond gears within each of the first, second, third, and fourth gearsets are co-planar.

In yet another aspect of the present invention, the input member, thefirst and second interconnecting members, and the first planetary gearset are co-axial and the third, fourth, and fifth interconnectingmembers, the second planetary gear set, and the third planetary gear setare co-axial.

In yet another aspect of the present invention, the output member isoffset from the first, second, third, fourth, and fifth interconnectingmembers and the input member.

In yet another aspect of the present invention, the stationary elementis a transmission housing.

Another embodiment of the transmission of the present invention includesan input member, an output member, a first, second, and third planetarygear set each having a first, second, and third member, wherein theinput member is continuously interconnected with the second member ofthe first planetary gear set, a first, second, third, and fourth gearset each having a first gear intermeshed with a second gear, wherein theoutput member is continuously interconnected with the second gear of thefourth gear set, a first interconnecting member continuouslyinterconnecting the first gear of the first gear set with the firstmember of the first planetary gear set, a second interconnecting membercontinuously interconnecting the third member of the first planetarygear set with the first gear of the second gear set, a thirdinterconnecting member continuously interconnecting the first gear ofthe third gear set with the second member of the second planetary gearset, a fourth interconnecting member continuously interconnecting thefirst member of the second planetary gear set with the second gear ofthe second gear set, a fifth interconnecting member continuouslyinterconnecting the first member of the third planetary gear set withthe first gear of the third gear set, and a sixth interconnecting membercontinuously interconnecting the second member of the third planetarygear set with the first gear of the fourth gear set. A first torquetransmitting mechanism is selectively engageable to interconnect thesecond gear of the third gear set with at least one of the second memberof the first planetary gear set and the input member, a second torquetransmitting mechanism is selectively engageable to interconnect atleast one of the third member of the first planetary gear set and thefirst gear of the second gear set with the second gear of the third gearset, a third torque transmitting mechanism is selectively engageable tointerconnect the second gear of the first gear set with the third memberof the third planetary gear set, a fourth torque transmitting mechanismis selectively engageable to interconnect the third member of the thirdplanetary gear set with the third member of the second planetary gearset, and a fifth torque transmitting mechanism is selectively engageableto interconnect at least one of the first gear of the first gear set andthe first member of the first planetary gear set with a stationaryelement. The torque transmitting mechanisms are selectively engageablein combinations of at least three to establish at least eight forwardspeed ratios and at least one reverse speed ratio between the inputmember and the output member.

In one aspect of the present invention, the first members are sun gears,the second members are carrier members, and the third members are ringgears.

In another aspect of the present invention, the first members of thefirst and third planetary gear sets are sun gears, the second members ofthe first and third planetary gear sets are carrier members, the thirdmembers of the first and third planetary gear sets are ring gears, thefirst member of the second planetary gear set is a carrier member, thesecond member of the second planetary gear set is a sun gear, and thethird member of the second planetary gear set is a ring gear.

In yet another aspect of the present invention, the first gears and thesecond gears within each of the first, second, third, and fourth gearsets are co-planar.

In yet another aspect of the present invention, the input member, thefirst and second interconnecting members, and the first planetary gearset are co-axial and wherein the third, fourth, and fifthinterconnecting members, the second planetary gear set, and the thirdplanetary gear set are co-axial.

In yet another aspect of the present invention, the output member isoffset from the first, second, third, fourth, and fifth interconnectingmembers and the input member.

In yet another aspect of the present invention, the stationary elementis a transmission housing.

Still another embodiment of the transmission of the present inventionincludes an input member, an output member, a first, second, and thirdplanetary gear set each having a sun gear, a carrier member, and a ringgear, wherein the input member is continuously interconnected with thecarrier member of the first planetary gear set, a first, second, third,and fourth gear set each having a first gear intermeshed with a secondgear, wherein the output member is continuously interconnected with thesecond gear of the fourth gear set, a first interconnecting membercontinuously interconnecting the first gear of the first gear set withthe sun gear of the first planetary gear set, a second interconnectingmember continuously interconnecting the ring gear of the first planetarygear set with the first gear of the second gear set, a thirdinterconnecting member continuously interconnecting the first gear ofthe third gear set with the carrier member of the second planetary gearset, a fourth interconnecting member continuously interconnecting thesun gear of the second planetary gear set with the second gear of thesecond gear set, a fifth interconnecting member continuouslyinterconnecting the sun gear of the third planetary gear set with thefirst gear of the third gear set, and a sixth interconnecting membercontinuously interconnecting the carrier member of the third planetarygear set with the first gear of the fourth gear set. A first torquetransmitting mechanism is selectively engageable to interconnect thesecond gear of the third gear set with at least one of the carriermember of the first planetary gear set and the input member, a secondtorque transmitting mechanism is selectively engageable to interconnectat least one of the ring gear of the first planetary gear set and thefirst gear of the second gear set with the second gear of the third gearset, a third torque transmitting mechanism is selectively engageable tointerconnect the second gear of the first gear set with the ring gear ofthe third planetary gear set, a fourth torque transmitting mechanism isselectively engageable to interconnect the ring gear of the thirdplanetary gear set with the ring gear of the second planetary gear set,and a fifth torque transmitting mechanism is selectively engageable tointerconnect at least one of the first gear of the first gear set andthe sun gear of the first planetary gear set with a stationary element.The torque transmitting mechanisms are selectively engageable incombinations of at least three to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.

In one aspect of the present invention, the input member, the first andsecond interconnecting members, and the first planetary gear set areco-axial and wherein the third, fourth, and fifth interconnectingmembers, the second planetary gear set, and the third planetary gear setare co-axial, and the output member is offset from the first, second,third, fourth, and fifth interconnecting members and the input member.

Still another embodiment of the transmission of the present inventionincludes an input member, an output member, a first, second, and thirdplanetary gear set each having a first, second, and ring gear, whereinthe input member is continuously interconnected with the carrier memberof the first planetary gear set, a first, second, third, and fourth gearset each having a first gear intermeshed with a second gear, wherein theoutput member is continuously interconnected with the second gear of thefourth gear set, a first interconnecting member continuouslyinterconnecting the first gear of the first gear set with the sun gearof the first planetary gear set, a second interconnecting membercontinuously interconnecting the ring gear of the first planetary gearset with the first gear of the second gear set, a third interconnectingmember continuously interconnecting the first gear of the third gear setwith the sun gear of the second planetary gear set, a fourthinterconnecting member continuously interconnecting the carrier memberof the second planetary gear set with the second gear of the second gearset, a fifth interconnecting member continuously interconnecting the sungear of the third planetary gear set with the first gear of the thirdgear set, and a sixth interconnecting member continuouslyinterconnecting the carrier member of the third planetary gear set withthe first gear of the fourth gear set. A first torque transmittingmechanism is selectively engageable to interconnect the second gear ofthe third gear set with at least one of the carrier member of the firstplanetary gear set and the input member, a second torque transmittingmechanism is selectively engageable to interconnect at least one of thering gear of the first planetary gear set and the first gear of thesecond gear set with the second gear of the third gear set, a thirdtorque transmitting mechanism is selectively engageable to interconnectthe second gear of the first gear set with the ring gear of the thirdplanetary gear set, a fourth torque transmitting mechanism isselectively engageable to interconnect the ring gear of the thirdplanetary gear set with the ring gear of the second planetary gear set,and a fifth torque transmitting mechanism is selectively engageable tointerconnect at least one of the first gear of the first gear set andthe sun gear of the first planetary gear set with a stationary element.The torque transmitting mechanisms are selectively engageable incombinations of at least three to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.

In one aspect of the present invention, the input member, the first andsecond interconnecting members, and the first planetary gear set areco-axial and wherein the third, fourth, and fifth interconnectingmembers, the second planetary gear set, and the third planetary gear setare co-axial, and the output member is offset from the first, second,third, fourth, and fifth interconnecting members and the input member.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of an eight speedtransmission according to the present invention;

FIG. 2 is a diagrammatic view of an embodiment of an eight speedtransmission according to the present invention;

FIG. 3 is a diagrammatic view of alternate embodiment of an eight speedtransmission according to the present invention; and

FIG. 4 is a truth table presenting the state of engagement of thevarious torque transmitting elements in each of the available forwardand reverse speeds or gear ratios of the transmissions illustrated inFIGS. 2 and 3.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

Referring now to FIG. 1, an embodiment of an eight speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a gear set.Solid line levers represent a planetary gear set wherein the three basicmechanical components of the planetary gear set are each represented bya node. Therefore, a single planetary gear set lever contains threenodes: one for the sun gear, one for the planet gear carrier, and onefor the ring gear. Dashed line levers are spur or external drive gearsets which may be represented in the lever diagram as planetary gearsets having grounded planet carrier members. Accordingly, the outernodes represent the first and second drive gears and the inner noderepresents the imaginary grounded planet carrier member. The relativelength between the nodes of each lever can be used to represent thering-to-sun ratio and first drive gear to second drive gear ratio ofeach respective gear set. These lever ratios, in turn, are used to varythe gear ratios of the transmission in order to achieve appropriateratios and ratio progression. Mechanical couplings or interconnectionsbetween the nodes of the various planetary gear sets are illustrated bythin, horizontal lines and torque transmitting devices such as clutchesand brakes are presented as interleaved fingers. Where the torquetransmitting device is a brake, one set of interleaved fingers iscoupled to a ground. Further explanation of the format, purpose and useof lever diagrams can be found in SAE Paper 810102, “The Lever Analogy:A New Tool in Transmission Analysis” by Benford and Leising which ishereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16C, athird planetary gear set 18 having three nodes: a first node 18A, asecond node 18B and a third node 18C, a first external gear set 20having three nodes: a first node 20A, a second node 20B and a third node20C, a second external gear set 22 having three nodes: a first node 22A,a second node 22B and a third node 22C, a second external gear set 24having three nodes: a first node 24A, a second node 24B and a third node24C, a fourth external gear set 26 having three nodes: a first node 26A,a second node 26B and a third node 26C, and an output shaft or member30.

The input member 12 is coupled to the second node 14B of the firstplanetary gear set 14. The output member 30 is coupled to the third node26C of the fourth external gear set 26. The first node 14A of the firstplanetary gear set 14 is coupled to the first node 20A of the firstexternal gear set 20. The third node 14C of the first planetary gear set14 is coupled to the first node 22A of the second external gear set 22.The first node 16A of the second planetary gear set 16 is coupled to thefirst node 18A of the third planetary gear set 18 and to the first node24A of the third external gear set 24. The third node 16C of the secondplanetary gear set 16 is coupled to the third node 22C of the secondexternal gear set 22. The second node 18B of the third planetary gearset 18 is coupled to the first node 26A of the fourth external gear set26.

A first clutch 40 selectively connects the second node 14B of the firstplanetary gear set 14 to the third node 24C of the third external gearset 24. A second clutch 42 selectively connects third node 14C of thefirst planetary gear set 14 and the first node 22A of the secondexternal gear set 22 to the third node 24C of the third external gearset 24. A third clutch 44 selectively connects the third node 20C of thefirst external gear set 20 to the third node 18C of the third planetarygear set 18. A fourth clutch 46 selectively connects the second node 16Bof the second planetary gear set 16 to the third node 18C of the thirdplanetary gear set 18. A first brake 48 selectively connects the firstnode 14A of the first planetary gear set 14 to a stationary element ortransmission housing 50.

Referring now to FIG. 2, a schematic diagram illustrates an embodimentof the eight speed transmission 10 according to the present invention.In FIG. 2, the numbering from the lever diagram of FIG. 1 is carriedover. The clutches, brake, and couplings or interconnections arecorrespondingly presented whereas the nodes of the planetary gear setsnow appear as components of planetary gear sets such as sun gears, ringgears, planet gears and planet gear carriers and the nodes of theexternal drive gear sets now appear as components of the external drivegear sets such as first and second drive gears.

For example, planetary gear set 14 includes a sun gear member 14A, aplanet gear carrier member 14B and a ring gear member 14C. The planetgear carrier member 14B rotatably supports a set of planet gears 14Dconfigured to intermesh with both the sun gear member 14A and the ringgear member 14C. The sun gear member 14A is connected for commonrotation with a first shaft or interconnecting member 52. The planetcarrier member 14B is connected for common rotation with the input shaftor member 12. The ring gear member 14C is connected for common rotationwith a second shaft or interconnecting member 54.

The planetary gear set 16 includes a sun gear member 16C, a planet gearcarrier member 16A and a ring gear member 16B. The planet gear carriermember 16A rotatably supports a first set of planet gears 16D and asecond set of planet gears 16E. First set of planet gears 16D areconfigured to intermesh with both second set of planet gears 16E and sungear member. Second set of planet gears 16E are configured to intermeshwith both first set of planet gears 16D and the ring gear member 16B.The sun gear member 16C is connected for common rotation with a thirdshaft or interconnecting member 56. The ring gear member 16B isconnected for common rotation with a fourth shaft or interconnectingmember 58. The planet carrier member 16A is connected for commonrotation with a fifth shaft or interconnecting member 60.

The planetary gear set 18 includes a sun gear member 18A, a planet gearcarrier member 18B and a ring gear member 18C. The planet gear carriermember 18B rotatably supports a set of planet gears 18D configured tointermesh with both the sun gear member 18A and the ring gear member18C. The sun gear member 18A is connected for common rotation with asixth shaft or interconnecting member 62. The ring gear member 18C isconnected for common rotation with a seventh shaft or interconnectingmember 64 and an eighth shaft or interconnecting member 66. The planetcarrier member 18B is connected for common rotation with a ninth shaftor interconnecting member 68.

The external gear set 20 includes a first gear member 20A intermeshedwith a second gear member 20C. The first gear member 20A is connectedfor common rotation with first shaft or interconnecting member 52. Thesecond gear member 20C is connected for common rotation with a tenthshaft or interconnecting member 70.

The external gear set 22 includes a first gear member 22A intermeshedwith a second gear member 22C. The first gear member 22A is connectedfor common rotation with the second shaft or interconnecting member 54and an eleventh shaft or interconnecting member 72. The second gearmember 22C is connected for common rotation with third interconnectingmember 56.

The external gear set 24 includes a first gear member 24A intermeshedwith a second gear member 24C. The first gear member 24A is connectedfor common rotation with fifth interconnecting member 60 and sixthinterconnecting member 62. The second gear member 24C is connected forcommon rotation with a twelfth shaft or interconnecting member 74.

The external gear set 26 includes a first gear member 26A intermeshedwith a second gear member 26C. The first gear member 26A is connectedfor common rotation with ninth shaft or interconnecting member 68. Thesecond gear member 26C is connected for common rotation with the outputmember 30.

The input shaft or member 12 is continuously connected to an engine (notshown) or to a turbine of a torque converter (not shown). The outputshaft or member 30 is continuously connected with the final drive unitor transfer case (not shown).

The torque-transmitting elements or the clutches 40, 42, 44, 46 andbrake 48 allow for selective interconnection of the shafts orinterconnecting members, members of the planetary gear sets and externalgear sets, and the transmission housing. For example, the first clutch40 is selectively engageable to connect the input member 12 with thetwelfth interconnecting member 74. The second clutch 42 is selectivelyengageable to connect the eleventh interconnecting member 72 with thetwelfth interconnecting member 74. The third clutch 44 is selectivelyengageable to connect the eighth interconnecting member 66 with thetenth interconnecting member 70. The fourth clutch 46 is selectivelyengageable to connect the fourth interconnecting member 58 with theseventh interconnecting member 64. The first brake 48 is selectivelyengageable to connect the first interconnecting member 52 to astationary element or the transmission housing 50 in order to restrictthe first interconnecting member 52 and therefore the first gear member20A and the sun gear member 14A from rotating relative to thetransmission housing 50.

In the particular example provided, the transmission 10 is arrangedalong three parallel and spaced apart axes including a first axisdefined by the input member 12, a second axis defined by the sixthinterconnecting member 62 and the ninth interconnecting member 68 and athird axis defined by the output member 30. Accordingly, in the exampleprovided, the interconnecting members 52, 54, 72 and 74, the planetarygear set 14, the first gear member 20A, the first gear member 22A, thesecond gear member 24C, the first brake 48 and the clutches 40, 42 areall coaxial with the first axis. The interconnecting members 56, 58, 60,62, 64, 66, and 70, the planetary gear sets 16 and 18, the second gearmember 20C, the second gear member 22C, the first gear member 24A, thefirst gear member 26A, the third clutch 44, the fourth clutch 46 are allcoaxial with the second axis. Finally, the second gear member 26C iscoaxial with the third axis. Additionally, the transmission 10 ispreferably configured for a front wheel drive vehicle.

With reference to FIG. 3, an alternate embodiment of the transmission ofthe present invention is illustrated schematically and generallyindicated by reference number 100. The transmission 100 and transmission10 include several of the same components, accordingly, like parts orcomponents are indicated by like reference numbers. However, the secondplanetary gear 16 is interconnected with the second gear member 22C andthe first gear member 24A through different shafts or interconnectingmembers 102 and 104. Shafts or interconnecting members 56 and 60 havebeen removed in the present embodiment. More specifically, the planetcarrier member 16A is connected for common rotation with second gearmember 22C by interconnecting member 102 and the sun gear member 16C isconnected for common rotation with the first gear member 24A byinterconnecting member 104. All other connections, couplings, clutches,brake and gear sets are similar to the arrangement disclosed in thetransmission 10 illustrated in FIG. 2.

Referring now to FIG. 4, the operation of the embodiments of the eightspeed transmission 10 and 100 will be described. It will be appreciatedthat transmissions 10 and 100 are capable of transmitting torque fromthe input shaft or member 12 to the output shaft or member 30 in atleast eight forward speed or torque ratios and at least one reversespeed or torque ratio. Each forward and reverse speed or torque ratio isattained by engagement of one or more of the torque-transmittingmechanisms (i.e. first clutch 40, second clutch 42, third clutch 44,fourth clutch 46, and first brake 48), as will be explained below. FIG.4 is a truth table presenting the various combinations oftorque-transmitting mechanisms that are activated or engaged to achievethe various gear states. Actual numerical gear ratios of the variousgear states are also presented although it should be appreciated thatthese numerical values are exemplary only and that they may be adjustedover significant ranges to accommodate various applications andoperational criteria of transmissions 10 and 100. An example of the gearratios that may be obtained using the embodiments of the presentinvention are also shown in FIG. 4. Of course, other gear ratios areachievable depending on the gear diameter, gear teeth count and gearconfiguration selected.

To establish the reverse gear, the third clutch 44, the fourth clutch46, and the first brake 48 are engaged or activated. The third clutch 44connects the eighth interconnecting member 66 with the tenthinterconnecting member 70. The fourth clutch 46 connects the fourthinterconnecting member 58 with the seventh interconnecting member 64.The first brake 48 connects the first interconnecting member 52 to astationary element or the transmission housing 50 in order to restrictthe first interconnecting member 52 and therefore the first gear member20A and the sun gear member 14A from rotating relative to thetransmission housing 50. Likewise, the eight forward ratios are achievedthrough different combinations of clutch and brake engagement, as shownin FIG. 4.

It will be appreciated that the foregoing explanation of operation andgear states of the eight speed transmission 10 assumes, first of all,that all the clutches and brakes not specifically referenced in a givengear state are inactive or disengaged and, second of all, that duringgear shifts, i.e., changes of gear state, between at least adjacent gearstates, a clutch or brake engaged or activated in both gear states willremain engaged or activated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; afirst, second, and third planetary gear set each having a first, second,and third member; a first, second, third, and fourth co-planar gear seteach having first gear intermeshed with a second gear; a firstinterconnecting member continuously interconnecting the first gear ofthe first co-planar gear set with the first member of the firstplanetary gear set; a second interconnecting member continuouslyinterconnecting the third member of the first planetary gear set withthe first gear of the second co-planar gear set; a third interconnectingmember continuously interconnecting the first gear of the thirdco-planar gear set with the second member of the second planetary gearset; a fourth interconnecting member continuously interconnecting thefirst member of the second planetary gear set with the second gear ofthe second co-planar gear set; a fifth interconnecting membercontinuously interconnecting the first member of the third planetarygear set with the first gear of the third co-planar gear set; a sixthinterconnecting member continuously interconnecting the second member ofthe third planetary gear set with the first gear of the fourth co-planargear set; and five torque transmitting mechanisms each selectivelyengageable to interconnect at least one of the first members, secondmembers, third members, first gears, and second gears with at least oneother of the first members, second members, third members, first gears,second gears, and a stationary element, and wherein the torquetransmitting mechanisms are selectively engageable in combinations of atleast three to establish at least eight forward speed ratios and atleast one reverse speed ratio between the input member and the outputmember.
 2. The transmission of claim 1 wherein a first of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe second gear of the third co-planar gear set with at least one of thesecond member of the first planetary gear set and the input member. 3.The transmission of claim 2 wherein a second of the five torquetransmitting mechanisms is selectively engageable to interconnect atleast one of the third member of the first planetary gear set and thefirst gear of the second co-planar gear set with the second gear of thethird co-planar gear set.
 4. The transmission of claim 3 wherein a thirdof the five torque transmitting mechanisms is selectively engageable tointerconnect the second gear of the first co-planar gear set with thethird member of the third planetary gear set.
 5. The transmission ofclaim 4 wherein a fourth of the five torque transmitting mechanisms isselectively engageable to interconnect the third member of the thirdplanetary gear set with the third member of the second planetary gearset.
 6. The transmission of claim 5 wherein a fifth of the five torquetransmitting mechanisms is selectively engageable to interconnect atleast one of the first gear of the first co-planar gear set and thefirst member of the first planetary gear set with the stationaryelement.
 7. The transmission of claim 1 wherein the input member iscontinuously interconnected with the second member of the firstplanetary gear set and wherein the output member is continuouslyinterconnected with the second gear of the fourth co-planar gear set. 8.The transmission of claim 1 wherein the first members are sun gears, thesecond members are carrier members, and the third members are ringgears.
 9. The transmission of claim 1 wherein the first members of thefirst and third planetary gear sets are sun gears, the second members ofthe first and third planetary gear sets are carrier members, the thirdmembers of the first and third planetary gear sets are ring gears, thefirst member of the second planetary gear set is a carrier member, thesecond member of the second planetary gear set is a sun gear, and thethird member of the second planetary gear set is a ring gear.
 10. Thetransmission of claim 6 wherein the first and second torque transmittingmechanisms are connected to the second gear of the third co-planar gearset by a first sleeve shaft, wherein the fifth torque transmittingmechanism is connected to the first gear of the first co-planar gear setand the first member of the first planetary gear set by a second sleeveshaft, and wherein the first and second sleeve shafts are concentricwith the input member.
 11. The transmission of claim 1 wherein the inputmember, the first and second interconnecting members, and the firstplanetary gear set are co-axial and wherein the third, fourth, and fifthinterconnecting members, the second planetary gear set, and the thirdplanetary gear set are co-axial, and wherein the output member is offsetfrom the first, second, third, fourth, and fifth interconnecting membersand the input member.
 12. The transmission of claim 6 wherein the fourthtorque transmitting mechanism is connected to the third member of thesecond planetary gear set by a third sleeve shaft, and wherein the thirdsleeve shaft is concentric with the fourth, fifth, and sixthinterconnecting members.
 13. The transmission of claim 1 wherein thestationary element is a transmission housing.
 14. A transmissioncomprising: an input member; an output member; a first, second, andthird planetary gear set each having a first, second, and third member,wherein the input member is continuously interconnected with the secondmember of the first planetary gear set; a first, second, third, andfourth co-planar gear set each having a first gear intermeshed with asecond gear, wherein the output member is continuously interconnectedwith the second gear of the fourth co-planar gear set; a firstinterconnecting member continuously interconnecting the first gear ofthe first co-planar gear set with the first member of the firstplanetary gear set; a second interconnecting member continuouslyinterconnecting the third member of the first planetary gear set withthe first gear of the second co-planar gear set; a third interconnectingmember continuously interconnecting the first gear of the thirdco-planar gear set with the second member of the second planetary gearset; a fourth interconnecting member continuously interconnecting thefirst member of the second planetary gear set with the second gear ofthe second co-planar gear set; a fifth interconnecting membercontinuously interconnecting the first member of the third planetarygear set with the first gear of the third co-planar gear set; a sixthinterconnecting member continuously interconnecting the second member ofthe third planetary gear set with the first gear of the fourth co-planargear set; a first torque transmitting mechanism selectively engageableto interconnect the second gear of the third co-planar gear set with atleast one of the second member of the first planetary gear set and theinput member; a second torque transmitting mechanism selectivelyengageable to interconnect at least one of the third member of the firstplanetary gear set and the first gear of the second co-planar gear setwith the second gear of the third co-planar gear set; a third torquetransmitting mechanism selectively engageable to interconnect the secondgear of the first co-planar gear set with the third member of the thirdplanetary gear set; a fourth torque transmitting mechanism selectivelyengageable to interconnect the third member of the third planetary gearset with the third member of the second planetary gear set; and a fifthtorque transmitting mechanism selectively engageable to interconnect atleast one of the first gear of the first co-planar gear set and thefirst member of the first planetary gear set with a stationary element,and wherein the torque transmitting mechanisms are selectivelyengageable in combinations of at least three to establish at least eightforward speed ratios and at least one reverse speed ratio between theinput member and the output member.
 15. The transmission of claim 14wherein the first members are sun gears, the second members are carriermembers, and the third members are ring gears.
 16. The transmission ofclaim 14 wherein the first members of the first and third planetary gearsets are sun gears, the second members of the first and third planetarygear sets are carrier members, the third members of the first and thirdplanetary gear sets are ring gears, the first member of the secondplanetary gear set is a carrier member, the second member of the secondplanetary gear set is a sun gear, and the third member of the secondplanetary gear set is a ring gear.
 17. The transmission of claim 14wherein the first gears and the second gears within each of the first,second, third, and fourth co-planar gear sets are co-planar.
 18. Thetransmission of claim 14 wherein the input member, the first and secondinterconnecting members, and the first planetary gear set are co-axialand wherein the third, fourth, and fifth interconnecting members, thesecond planetary gear set, and the third planetary gear set areco-axial.
 19. The transmission of claim 14 wherein the output member isoffset from the first, second, third, fourth, and fifth interconnectingmembers and the input member.
 20. The transmission of claim 14 whereinthe stationary element is a transmission housing.
 21. A transmissioncomprising: an input member; an output member; a first, second, andthird planetary gear set each having a sun gear, a carrier member, and aring gear, wherein the input member is continuously interconnected withthe carrier member of the first planetary gear set; a first, second,third, and fourth co-planar gear set each having a first gearintermeshed with a second gear, wherein the output member iscontinuously interconnected with the second gear of the fourth co-planargear set; a first interconnecting member continuously interconnectingthe first gear of the first co-planar gear set with the sun gear of thefirst planetary gear set; a second interconnecting member continuouslyinterconnecting the ring gear of the first planetary gear set with thefirst gear of the second co-planar gear set; a third interconnectingmember continuously interconnecting the first gear of the thirdco-planar gear set with the carrier member of the second planetary gearset; a fourth interconnecting member continuously interconnecting thesun gear of the second planetary gear set with the second gear of thesecond co-planar gear set; a fifth interconnecting member continuouslyinterconnecting the sun gear of the third planetary gear set with thefirst gear of the third co-planar gear set; a sixth interconnectingmember continuously interconnecting the carrier member of the thirdplanetary gear set with the first gear of the fourth co-planar gear set;a first torque transmitting mechanism selectively engageable tointerconnect the second gear of the third co-planar gear set with atleast one of the carrier member of the first planetary gear set and theinput member; a second torque transmitting mechanism selectivelyengageable to interconnect at least one of the ring gear of the firstplanetary gear set and the first gear of the second co-planar gear setwith the second gear of the third co-planar gear set; a third torquetransmitting mechanism selectively engageable to interconnect the secondgear of the first co-planar gear set with the ring gear of the thirdplanetary gear set; a fourth torque transmitting mechanism selectivelyengageable to interconnect the ring gear of the third planetary gear setwith the ring gear of the second planetary gear set; and a fifth torquetransmitting mechanism selectively engageable to interconnect at leastone of the first gear of the first co-planar gear set and the sun gearof the first planetary gear set with a stationary element, and whereinthe torque transmitting mechanisms are selectively engageable incombinations of at least three to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.
 22. The transmission of claim 21 wherein the inputmember, the first and second interconnecting members, and the firstplanetary gear set are co-axial and wherein the third, fourth, and fifthinterconnecting members, the second planetary gear set, and the thirdplanetary gear set are co-axial, and wherein the output member is offsetfrom the first, second, third, fourth, and fifth interconnecting membersand the input member.
 23. A transmission comprising: an input member; anoutput member; a first, second, and third planetary gear set each havinga sun gear, a carrier member, and a ring gear, wherein the input memberis continuously interconnected with the carrier member of the firstplanetary gear set; a first, second, third, and fourth co-planar gearset each having a first gear intermeshed with a second gear, wherein theoutput member is continuously interconnected with the second gear of thefourth co-planar gear set; a first interconnecting member continuouslyinterconnecting the first gear of the first co-planar gear set with thesun gear of the first planetary gear set; a second interconnectingmember continuously interconnecting the ring gear of the first planetarygear set with the first gear of the second co-planar gear set; a thirdinterconnecting member continuously interconnecting the first gear ofthe third co-planar gear set with the sun gear of the second planetarygear set; a fourth interconnecting member continuously interconnectingthe carrier member of the second planetary gear set with the second gearof the second co-planar gear set; a fifth interconnecting membercontinuously interconnecting the sun gear of the third planetary gearset with the first gear of the third co-planar gear set; a sixthinterconnecting member continuously interconnecting the carrier memberof the third planetary gear set with the first gear of the fourthco-planar gear set; a first torque transmitting mechanism selectivelyengageable to interconnect the second gear of the third co-planar gearset with at least one of the carrier member of the first planetary gearset and the input member; a second torque transmitting mechanismselectively engageable to interconnect at least one of the ring gear ofthe first planetary gear set and the first gear of the second co-planargear set with the second gear of the third co-planar gear set; a thirdtorque transmitting mechanism selectively engageable to interconnect thesecond gear of the first co-planar gear set with the ring gear of thethird planetary gear set; a fourth torque transmitting mechanismselectively engageable to interconnect the ring gear of the thirdplanetary gear set with the ring gear of the second planetary gear set;and a fifth torque transmitting mechanism selectively engageable tointerconnect at least one of the first gear of the first co-planar gearset and the sun gear of the first planetary gear set with a stationaryelement, and wherein the torque transmitting mechanisms are selectivelyengageable in combinations of at least three to establish at least eightforward speed ratios and at least one reverse speed ratio between theinput member and the output member.
 24. The transmission of claim 23wherein the input member, the first and second interconnecting members,and the first planetary gear set are co-axial and wherein the third,fourth, and fifth interconnecting members, the second planetary gearset, and the third planetary gear set are co-axial, and wherein theoutput member is offset from the first, second, third, fourth, and fifthinterconnecting members and the input member.